Contribution of Key Odorants from Skins, Seeds, and Stems to the Aroma of Chardonnay Marc: A Valuable Coproduct of the Wine Industry

Chardonnay marc, a co-product of the wine making industry, has recently garnered attention due to its health-promoting properties and is growing in popularity as a potential healthy and flavorful food ingredient. While previous studies have characterized the odorants in marc skins and identified the key odorants in marc seeds, the key odorants in the skins and stems and the contribution of each component to the whole marc aroma remains unknown. In this study, 27 odorants were identified in marc stems using solvent-assisted flavor evaporation and aroma extract dilution analysis. Four odorants were quantitated employing stable isotope dilution assays, and odor activity values (OAVs) were calculated. An odor simulation model prepared using odorants with OAVs > 1 sensorially matched the aroma of the marc stems. Omission studies showed that 3-methylnonane-2,4-dione, ethyl octanoate, oct-1-en-3-one, (2E,4E)-deca-2,4-dienal, (2E,4E)-nona-2,4-dienal, β-ionone, linalool, hexanal, HDMF, and 3-(methylsulfonyl)propanal were the key odorants in marc skins, while hexanal and 3-methylnonane-2,4-dione were the key odorants in marc stems. Mass balance studies suggested that the skins were the main contributor to the hay, floral, and fruity attributes of the whole marc, the seeds contributed mostly to the fatty attribute, and the stems had a minor contribution.

Characterization of Key Odorants in Chardonnay Seeds

Chardonnay marc, a co-product of the winemaking industry, is a combination of skins, seeds, and stems remaining after the juice is pressed from the grapes. This co-product amounts to over half a million tons per year. Recently, Chardonnay marc has been emerging as a healthy and flavorful food ingredient. The aroma contribution of the seeds to the overall aroma of Chardonnay marc remains unknown. In the present study, 43 odorants were identified in Chardonnay seeds employing aroma extract dilution analysis (AEDA) performed on a distillate prepared by solvent extraction and solvent-assisted flavor evaporation (SAFE) distillation. Of those, 6 odorants with a flavor dilution (FD) factor ≥64 were quantitated using stable isotope dilution assays (SIDAs). The odorants included (2E,4E)-deca-2,4-dienal (fatty, OAV 8028), 3-methylnonane-2,4-dione (hay, OAV 4772), (2E,4E)-nona-2,4-dienal (fatty, OAV 1750), hexanal (green, OAV 1481), linalool (floral, citrus, OAV 28), and 2-phenylethanol (floral, rose, OAV 2). An aroma simulation model was prepared based on the quantitative data, and its aroma was a close match to the Chardonnay seed powder. Omission studies applied to the aroma simulation model showed that hexanal and 3-methylnonane-2,4-dione were the key odorants driving the aroma profile. This research established a foundation for future studies aimed at optimizing the flavor of Chardonnay marc powder.